Returns an integer that specifies the end position of the current Range relative to the endContainer element.

Note: The Range object and its endOffset property are supported in Internet Explorer from version 9.

If the node referred to by the endContainer property is a TextNode, CDATASection or CommentNode, then the
endOffset property returns a character position in the text content of the referred node.
For other node types, the returned value is an index into the childNodes collection of the node.

Note that the end point is not part of the Range (it is the first position after), therefore the value returned by the
endOffset property can be equal to the length of the text content or childNodes collection of the node referred to by the endContainer property.